A cashel is a type of ringfort defined by its stone construction rather than earthen banks, and this distinction matters: where an earthen ringfort might erode into little more than a subtle rise in a field, a cashel can persist for centuries as a visible ring of drystone walling, stubborn against the weather in ways that soil simply is not. That this one carries both names, ringfort and cashel, suggests it belongs to that category of early medieval enclosure built to define and defend a farmstead, probably somewhere between the sixth and twelfth centuries, when this form of settlement was widespread across Ireland.

Cashels of this kind were typically the homes of farming families of some local standing, the stone walls serving as much to contain livestock and signal territorial ownership as to provide any serious military defence. Mayo has no shortage of them, particularly in areas where surface stone was plentiful and timber scarce, and Coollagagh sits within a county whose early medieval archaeology remains, in many places, only partially studied. The specific history of this particular enclosure, its dimensions, its condition, the presence of any internal features such as a house platform or souterrain, a roofed underground passage sometimes used for storage or refuge, is not currently documented in any accessible public record.